In the case of detecting smoke, fire, and high heat in a building, it is desirable to cut off the flow of air within the entire building to prevent smoke from circulating, fire from burning, and to retard heat flow. Automatically closing fire dampers for air ducts are well known. However, these automatic closable damper devices only operate in the room in which the fire occurs. Additionally, most buildings have a ventilation system, such as an air conditioner or a furnace, which includes a blower for circulating air in the building. If the blower is allowed to operate during, for example, a fire the circulated air will feed the fire. Therefore, in addition to closing the vents, the blower is usually disabled.
The possibility of carbon monoxide poisoning is a serious safety hazard. Carbon monoxide accounts for one half the fatal poisoning in the United States each year, from a minimum of about 200 to as many as 1500. Carbon monoxide is a serious hazard because of its strong attraction to hemoglobin which normally combines with oxygen in the lungs and carries it throughout the body. When carbon monoxide is present, it replaces the oxygen and, in high enough concentration, poisoning can result.
Carbon monoxide is a by-product of incomplete combustion. Since it is odorless and colorless, there is no warning of its presence. Carbon monoxide sources include automobile exhaust fumes, furnaces, kitchen gas ranges, water heaters, fireplaces, charcoal grills, and small gasoline engine operated equipment. Moreover, with the current concern for energy efficiency, many recently built homes do not provide adequate fresh air flow. Homes are tighter because of more insulation, caulking, insulating window films and weather stripping. If there is inadequate fresh air flow, the opportunity arises for carbon monoxide build-up. Carbon monoxide poisoning is more of a problem during the winter because heating systems are running.
While precautions can be taken to minimize the possibility of carbon monoxide poisoning, accidental leaks do occur, so it is advisable to utilize carbon monoxide detectors. Chemical detectors are available which are the least expensive but require monitoring. These use carbon monoxide sensitive chemicals which change color when exposed to a specified level of the gas. Electronic detectors are more expensive but do not need to be monitored as they sound an alarm when specified levels of carbon monoxide are present.